[robododo]

So... plastic + blue foam + blue foam + plastic.

This sounds extremely flammable. Are any of your materials actually code-rated for a living structure (as you're using them)? Last I checked, stuff like blue foam board needs to be used in specific ways, such as behind fire-rated walls. You cannot leave any of it exposed, or it's a fire hazard.

[dugmartin]

Flame retardant corrugated plastic sheets do exist (my brother used several hundred of them for an event inside a hotel). I'm not sure if it would be enough of a firewall for blueboard though.